Tutorial III - Spatial Analyst

From your PC, navigate to the network workgroup computer, "slush." Click on "gis." Click on Nicaragua. Click on laharz.

Copy the mudflow shapefile to your workspace directory using ArcCatalog.

Load ArcMap

Add the following coverages from your workspace directory: concepcion_sh, conceproads, and mudflow.

Note that the mudflow loads as a binary dataset (i.e. a flow and its surroundings). In the layer column, right click on mudflow and select "Open Attribute Table." On the bottom right corner, select "Options". Click "Select by Attributes." You are interested in isolating just the mudflow, which is the item with the lowest count. Therefore, select "Object ID" on the top left of the pop-up and then select "=." Pick the number with the lowest cell count (i.e. 12636). Click "Apply." Click "Close." Now close the attribute table using the exit button on the top right corner.

If the Spatial Analyst is not loaded on the toolbar, click on the "View" menu and select toolbars. Click on Spatial Analyst.

Click on the Spatial Analyst on the toolbar. Select "Convert" and then click on "Raster to Features." Make sure that the "Generalize Lines" box is unchecked. Click on the file icon and name your file "lahar". Select "Save" and click Ok.

Remove the mudflow coverage from the layers column. You have now created a shapefile for the mudflow, or lahar, from the binary raster file. Shapefiles are significantly smaller in size than raster files, and thus load much faster.